Re: [PATCH V5 1/2] Add overflow API for plus minus mult on range

[Andrew MacLeod <amacleod@redhat.com>]

This is OK.


On 8/2/23 22:18, Jiufu Guo wrote:
> Hi,
>
> I would like to have a ping on this patch.
>
> BR,
> Jeff (Jiufu Guo)
>
>
> Jiufu Guo <guojiufu@linux.ibm.com> writes:
>
>> Hi,
>>
>> As discussed in previous reviews, adding overflow APIs to range-op
>> would be useful. Those APIs could help to check if overflow happens
>> when operating between two 'range's, like: plus, minus, and mult.
>>
>> Previous discussions are here:
>> https://gcc.gnu.org/pipermail/gcc-patches/2023-July/624067.html
>> https://gcc.gnu.org/pipermail/gcc-patches/2023-July/624701.html
>>
>> Bootstrap & regtest pass on ppc64{,le} and x86_64.
>> Is this patch ok for trunk?
>>
>> BR,
>> Jeff (Jiufu Guo)
>>
>> gcc/ChangeLog:
>>
>> 	* range-op-mixed.h (operator_plus::overflow_free_p): New declare.
>> 	(operator_minus::overflow_free_p): New declare.
>> 	(operator_mult::overflow_free_p): New declare.
>> 	* range-op.cc (range_op_handler::overflow_free_p): New function.
>> 	(range_operator::overflow_free_p): New default function.
>> 	(operator_plus::overflow_free_p): New function.
>> 	(operator_minus::overflow_free_p): New function.
>> 	(operator_mult::overflow_free_p): New function.
>> 	* range-op.h (range_op_handler::overflow_free_p): New declare.
>> 	(range_operator::overflow_free_p): New declare.
>> 	* value-range.cc (irange::nonnegative_p): New function.
>> 	(irange::nonpositive_p): New function.
>> 	* value-range.h (irange::nonnegative_p): New declare.
>> 	(irange::nonpositive_p): New declare.
>>
>> ---
>>   gcc/range-op-mixed.h |  11 ++++
>>   gcc/range-op.cc      | 124 +++++++++++++++++++++++++++++++++++++++++++
>>   gcc/range-op.h       |   5 ++
>>   gcc/value-range.cc   |  12 +++++
>>   gcc/value-range.h    |   2 +
>>   5 files changed, 154 insertions(+)
>>
>> diff --git a/gcc/range-op-mixed.h b/gcc/range-op-mixed.h
>> index 6944742ecbc..42157ed9061 100644
>> --- a/gcc/range-op-mixed.h
>> +++ b/gcc/range-op-mixed.h
>> @@ -383,6 +383,10 @@ public:
>>   				  relation_kind rel) const final override;
>>     void update_bitmask (irange &r, const irange &lh,
>>   		       const irange &rh) const final override;
>> +
>> +  virtual bool overflow_free_p (const irange &lh, const irange &rh,
>> +				relation_trio = TRIO_VARYING) const;
>> +
>>   private:
>>     void wi_fold (irange &r, tree type, const wide_int &lh_lb,
>>   		const wide_int &lh_ub, const wide_int &rh_lb,
>> @@ -446,6 +450,10 @@ public:
>>   				relation_kind rel) const final override;
>>     void update_bitmask (irange &r, const irange &lh,
>>   		       const irange &rh) const final override;
>> +
>> +  virtual bool overflow_free_p (const irange &lh, const irange &rh,
>> +				relation_trio = TRIO_VARYING) const;
>> +
>>   private:
>>     void wi_fold (irange &r, tree type, const wide_int &lh_lb,
>>   		const wide_int &lh_ub, const wide_int &rh_lb,
>> @@ -525,6 +533,9 @@ public:
>>   		const REAL_VALUE_TYPE &lh_lb, const REAL_VALUE_TYPE &lh_ub,
>>   		const REAL_VALUE_TYPE &rh_lb, const REAL_VALUE_TYPE &rh_ub,
>>   		relation_kind kind) const final override;
>> +  virtual bool overflow_free_p (const irange &lh, const irange &rh,
>> +				relation_trio = TRIO_VARYING) const;
>> +
>>   };
>>   
>>   class operator_addr_expr : public range_operator
>> diff --git a/gcc/range-op.cc b/gcc/range-op.cc
>> index cb584314f4c..632b044331b 100644
>> --- a/gcc/range-op.cc
>> +++ b/gcc/range-op.cc
>> @@ -366,6 +366,22 @@ range_op_handler::op1_op2_relation (const vrange &lhs) const
>>       }
>>   }
>>   
>> +bool
>> +range_op_handler::overflow_free_p (const vrange &lh,
>> +				   const vrange &rh,
>> +				   relation_trio rel) const
>> +{
>> +  gcc_checking_assert (m_operator);
>> +  switch (dispatch_kind (lh, lh, rh))
>> +    {
>> +      case RO_III:
>> +	return m_operator->overflow_free_p(as_a <irange> (lh),
>> +					   as_a <irange> (rh),
>> +					   rel);
>> +      default:
>> +	return false;
>> +    }
>> +}
>>   
>>   // Convert irange bitmasks into a VALUE MASK pair suitable for calling CCP.
>>   
>> @@ -688,6 +704,13 @@ range_operator::op1_op2_relation_effect (irange &lhs_range ATTRIBUTE_UNUSED,
>>     return false;
>>   }
>>   
>> +bool
>> +range_operator::overflow_free_p (const irange &, const irange &,
>> +				 relation_trio) const
>> +{
>> +  return false;
>> +}
>> +
>>   // Apply any known bitmask updates based on this operator.
>>   
>>   void
>> @@ -4311,6 +4334,107 @@ range_op_table::initialize_integral_ops ()
>>   
>>   }
>>   
>> +bool
>> +operator_plus::overflow_free_p (const irange &lh, const irange &rh,
>> +				relation_trio) const
>> +{
>> +  if (lh.undefined_p () || rh.undefined_p ())
>> +    return false;
>> +
>> +  tree type = lh.type ();
>> +  if (TYPE_OVERFLOW_UNDEFINED (type))
>> +    return true;
>> +
>> +  wi::overflow_type ovf;
>> +  signop sgn = TYPE_SIGN (type);
>> +  wide_int wmax0 = lh.upper_bound ();
>> +  wide_int wmax1 = rh.upper_bound ();
>> +  wi::add (wmax0, wmax1, sgn, &ovf);
>> +  if (ovf != wi::OVF_NONE)
>> +    return false;
>> +
>> +  if (TYPE_UNSIGNED (type))
>> +    return true;
>> +
>> +  wide_int wmin0 = lh.lower_bound ();
>> +  wide_int wmin1 = rh.lower_bound ();
>> +  wi::add (wmin0, wmin1, sgn, &ovf);
>> +  if (ovf != wi::OVF_NONE)
>> +    return false;
>> +
>> +  return true;
>> +}
>> +
>> +bool
>> +operator_minus::overflow_free_p (const irange &lh, const irange &rh,
>> +				 relation_trio) const
>> +{
>> +  if (lh.undefined_p () || rh.undefined_p ())
>> +    return false;
>> +
>> +  tree type = lh.type ();
>> +  if (TYPE_OVERFLOW_UNDEFINED (type))
>> +    return true;
>> +
>> +  wi::overflow_type ovf;
>> +  signop sgn = TYPE_SIGN (type);
>> +  wide_int wmin0 = lh.lower_bound ();
>> +  wide_int wmax1 = rh.upper_bound ();
>> +  wi::sub (wmin0, wmax1, sgn, &ovf);
>> +  if (ovf != wi::OVF_NONE)
>> +    return false;
>> +
>> +  if (TYPE_UNSIGNED (type))
>> +    return true;
>> +
>> +  wide_int wmax0 = lh.upper_bound ();
>> +  wide_int wmin1 = rh.lower_bound ();
>> +  wi::sub (wmax0, wmin1, sgn, &ovf);
>> +  if (ovf != wi::OVF_NONE)
>> +    return false;
>> +
>> +  return true;
>> +}
>> +
>> +bool
>> +operator_mult::overflow_free_p (const irange &lh, const irange &rh,
>> +				relation_trio) const
>> +{
>> +  if (lh.undefined_p () || rh.undefined_p ())
>> +    return false;
>> +
>> +  tree type = lh.type ();
>> +  if (TYPE_OVERFLOW_UNDEFINED (type))
>> +    return true;
>> +
>> +  wi::overflow_type ovf;
>> +  signop sgn = TYPE_SIGN (type);
>> +  wide_int wmax0 = lh.upper_bound ();
>> +  wide_int wmax1 = rh.upper_bound ();
>> +  wi::mul (wmax0, wmax1, sgn, &ovf);
>> +  if (ovf != wi::OVF_NONE)
>> +    return false;
>> +
>> +  if (TYPE_UNSIGNED (type))
>> +    return true;
>> +
>> +  wide_int wmin0 = lh.lower_bound ();
>> +  wide_int wmin1 = rh.lower_bound ();
>> +  wi::mul (wmin0, wmin1, sgn, &ovf);
>> +  if (ovf != wi::OVF_NONE)
>> +    return false;
>> +
>> +  wi::mul (wmin0, wmax1, sgn, &ovf);
>> +  if (ovf != wi::OVF_NONE)
>> +    return false;
>> +
>> +  wi::mul (wmax0, wmin1, sgn, &ovf);
>> +  if (ovf != wi::OVF_NONE)
>> +    return false;
>> +
>> +  return true;
>> +}
>> +
>>   #if CHECKING_P
>>   #include "selftest.h"
>>   
>> diff --git a/gcc/range-op.h b/gcc/range-op.h
>> index af94c2756a7..db3b03f28a5 100644
>> --- a/gcc/range-op.h
>> +++ b/gcc/range-op.h
>> @@ -147,6 +147,9 @@ public:
>>   
>>     virtual relation_kind op1_op2_relation (const irange &lhs) const;
>>     virtual relation_kind op1_op2_relation (const frange &lhs) const;
>> +
>> +  virtual bool overflow_free_p (const irange &lh, const irange &rh,
>> +				relation_trio = TRIO_VARYING) const;
>>   protected:
>>     // Perform an integral operation between 2 sub-ranges and return it.
>>     virtual void wi_fold (irange &r, tree type,
>> @@ -214,6 +217,8 @@ public:
>>   				  const vrange &op2,
>>   				  relation_kind = VREL_VARYING) const;
>>     relation_kind op1_op2_relation (const vrange &lhs) const;
>> +  bool overflow_free_p (const vrange &lh, const vrange &rh,
>> +			relation_trio = TRIO_VARYING) const;
>>   protected:
>>     unsigned dispatch_kind (const vrange &lhs, const vrange &op1,
>>   			  const vrange& op2) const;
>> diff --git a/gcc/value-range.cc b/gcc/value-range.cc
>> index 011bdbdeae6..5ae4e044194 100644
>> --- a/gcc/value-range.cc
>> +++ b/gcc/value-range.cc
>> @@ -313,6 +313,18 @@ add_vrange (const vrange &v, inchash::hash &hstate,
>>   
>>   } //namespace inchash
>>   
>> +bool
>> +irange::nonnegative_p () const
>> +{
>> +  return wi::ge_p (lower_bound (), 0, TYPE_SIGN (type ()));
>> +}
>> +
>> +bool
>> +irange::nonpositive_p () const
>> +{
>> +  return wi::le_p (upper_bound (), 0, TYPE_SIGN (type ()));
>> +}
>> +
>>   bool
>>   irange::supports_type_p (const_tree type) const
>>   {
>> diff --git a/gcc/value-range.h b/gcc/value-range.h
>> index 0170188201b..a12dea514e4 100644
>> --- a/gcc/value-range.h
>> +++ b/gcc/value-range.h
>> @@ -280,6 +280,8 @@ public:
>>     virtual bool singleton_p (tree *result = NULL) const override;
>>     bool singleton_p (wide_int &) const;
>>     bool contains_p (const wide_int &) const;
>> +  bool nonnegative_p () const;
>> +  bool nonpositive_p () const;
>>   
>>     // In-place operators.
>>     virtual bool union_ (const vrange &) override;